当剪切和粘结比弯曲强的预应力受弯构件受荷失效时，它们会以下列方式中的一种失效：
    （1） Failure at cracking load           In very lightly prestressed members, the cracking moment may be greater than the moment the member can withstand in the cracked condition and, hence, the cracking moment is the ultimate moment. This condition is rare（很少的）and is most likely to occur in members that are prestressed concentrically with small amounts of steel. It can also occur in hollow or solid（实心）prestressed concrete members that have relatively low levels of reinforcing. Determination of the possibility of this type of failure is accomplished by comparing the estimated moment that would cause cracking to the estimated ultimate moment, computed as described below. When the estimated cracking load is larger than the computed ultimate load, this type of failure would take place if the member were subjected to the required loads. Because this type of failure is brittle failure, it occurs without warning – designs that would yield（产生）this mode of failure should be avoided.
    （1）开裂荷载下的失效              在施加非常少量预应力的构件中，其开裂弯矩可能大于构件在开裂状态下能承受的弯矩，因此，开裂弯矩为极限弯矩。这种情况是很少的，且在构件中最可能发生用少量钢筋同心地施加预应力。在空心或实心的预应力混凝土构件中也会出现相对低等级的钢筋。 通过比较引起开裂的弯矩估计值与按下面描述（的方法）计算的极限弯矩估计值来确定这种失效的可能性。当估计的开裂荷载大于计算的极限荷载，则如果构件承受要求的荷载，这种失效将会发生。由于这种失效是脆性失效，因此其发生时没有警告-产生这种失效方式的设计应该被避免。
    （2）Failure due to rupture of steel      In lightly reinforced（少量加筋）members subjected to ultimate load, the ultimate strength of the steel may be attained before the concrete has reached a highly plastic state（高度塑性状态）. This type of failure is occasionally encountered in the design of structures with very large compression flanges in comparison to（与..相比）the amount of prestressing steel, such as a composite（复合）bridge stringer（纵梁）. Computation of the ultimate moment of a member subject to this type of failure can be done with a high precision. The method of computation, as well as the determination of which members are subject to this mode of failure, is described below.
    （2）钢筋断裂引起的失效             在少量加筋并承受极限荷载的构件中，钢筋的极限强度可能在混凝土达到高度塑性状态之前就达到。这种失效在与预应力筋的数量相比有很大受压翼缘的结构设计中会偶然遇到，如一个复合的桥梁纵梁。可以高精度地计算易遭受这种失效的构件的极限弯矩。这种计算方法以及确定哪根杆件易遭受这种失效方式将在下面描述。
    （3）Failure due to strain     The usual underreinforced（配筋不足）, prestressed structure that are encountered in practice are of such proportions（尺寸）that, if loaded to ultimate, the steel would be stressed well into（早已进入）the plastic range and the member would evidence（显示）large deflection. Failure of the member will occur when the concrete attains the maximum strain that it is capable of withstanding. It is important to understand that research into（..的调查）the ultimate bending strength of reinforced and prestressed concrete has led most investigators to the conclusion that concrete, of the quality（特性）normally（通常）encountered in prestressed work（工程）fails when the limiting strain of 0.003 is attained in the concrete.
应变引起的失效            在实践中遇到通常配筋不足的预应力结构具有这样的尺寸，以至于如果加荷至极限，钢筋的应力早已进入塑性范围，而该构件将显示出很大的挠度。当混凝土达到其能承受的最大应变时，该构件将发生失效。明白对预应力钢筋混凝土的极限抗弯强度的调查已经导致多数调查者得到了结论，即当混凝土达到 0.003的极限应变时，具有在预应力工程中常遇性能的混凝土会失效，这点很重要。
            Since the ultimate bending capacity is limited by strain rather than stress in the concrete, it is a function of the elastic moduli（modulus的复数形式,模量）of the concrete and steel. The magnitude of the ultimate moment for members of this category can also be predicted（预测）, as a rule, within the normal tolerance（正常的允许误差）expected in structural design. The ultimate moment of underreinforced sections cannot be predicted with the same precision as the lightly reinforced members described above, since the ultimate moments of underreinforced members are a function of the elastic properties of the steel and the effective stresses in the prestressing steel, whereas the ultimate moment capacities of lightly reinforced members are not.